Lipoprotein fraction analysis is a valuable tool in estimating the risk for coronary artery disease. The current procedure, however, requires multiple tests and has several manual steps. In order to reduce the complexity and cost of lipoprotein fraction analysis, we have developed a single-tube homogenous assay for measuring serum high-density lipoprotein (HDL) cholesterol, total cholesterol, and triglyceride. Low-density lipoprotein (LDL) cholesterol can then be calculated from these parameters using the Friedewald equation. The assay uses an anti-apoB antibody to block the reactivity of the reporter enzymes to LDL-cholesterol. The assay is performed in a sequential manner so that after the HDL-cholesterol is determined, a detergent is added to disrupt the antibody complex, which allows the subsequent measurement of total cholesterol. Next, the reporter enzymes for measuring total triglyceride are added. In the upcoming year, we plan to test the compatibility of the method with alternative approaches for blocking the reactivity of LDL-cholesterol. We also plan to develop a homogenous assay for LDL-cholesterol, followed by sequential assays for total cholesterol and triglyceride.